Sensory analysis of olive oil
The sensory analysis of olive oil is a strategic tool with which the oil industries can raise production quality standards.
Sensory analysis is performed by using “tasting senses”, i.e. smell and taste.
The stages of olive oil tasting
In the first phase, the taster takes the glass, which he/she covers with the lid, tilting it slightly and in this position turning it completely to wet the inner surface as much as possible
Once this is done, the taster removes the lid from the glass and smells the sample, making slow and deep inhalations, in order to evaluate it.
Once these procedures comprising the olfactory phase have been concluded, the taster proceeds to the evaluation of oral sensations (combined olfactory-taste sensation by retronasal and tactile methods).
At this point, the taster takes a sip of oil of about 3 ml; it is important to distribute the oil throughout the oral cavity, from the front and tongue, passing over the sides and back, to the veli palatini and throat because, as is well known, the perception of flavours and tactile sensations varies in intensity according to the areas of the tongue, palate and throat that are stimulated.
The oil must spread in sufficient quantity and very slowly from the back of the tongue towards the veli palatini and throat, focusing on the order of emergence of the bitter and pungent (spicy/peppery) stimuli; otherwise, for some oils, the two stimuli may go unnoticed, or the bitterness may be covered by the pungency.
Short, successive aspirations through the mouth make it possible both to extend the sample into the oral cavity and to perceive the volatile aromatic components by forced passage through the retronasal route.
The assessment form must list the sensations experienced during the various tasting phases. They are divided into positive attributes: fruity, bitter and pungent.
Olive oil that is fruity, bitter and pungent
Fruitiness refers to the set of olfactory sensations, dependent on the variety of olives, and characteristic of oil obtained from healthy, fresh, green or ripe fruit, perceived directly or retronasally. It is reminiscent of the smell and taste of healthy, fresh fruit picked at the optimum point of ripeness. On tasting, a green fruitiness can be distinguished from a ripe fruitiness. The first is more intense, the second is milder and sweeter;
Bitterness is the elemental flavour characteristic of oil obtained from green or pitted olives, perceived by the calyciform papillae forming the lingual V-shaped groove.
Pungency (spicy or peppery sensation) is the tactile tingling sensation characteristic of oils produced at the beginning of the harvest, mainly from olives that are still green, which can be perceived throughout the oral cavity, particularly in the throat.
Negative attributes of olive oil
We say that oil is fusty or evokes a sludge flavour when it has been obtained from olives piled or stored in conditions that have favoured considerable anaerobic fermentation. This attribute also describes the flavour of oil in contact with decanting sludge in tanks or vats in which anaerobic fermentation processes have also taken place.
Other negative characteristics that can be attributed to the oil are musty, humid or earthy flavours. Generally, in these cases, the oil has been obtained from olives which have remained heaped in damp environments for many days, developing fungi and yeasts, or the olives have been picked from the ground or were soiled with dirt and not washed.
Negative attributes that the oil may have include a winey or vinegary flavour or an acid-sour sensation due to an aerobic fermentation process of olives or olive paste left in improperly washed mats, which leads to the formation of acetic acid, ethyl acetate and ethanol.
The condition of the olives chosen for oil production is clearly essential to the success of the product. Indeed, if frozen olives are used, the result of a bad harvest, or which have undergone prolonged storage before processing at the mill, the flavour will be adversely affected.
Other types of olive oil defects may be caused by poor storage; this is the case of rancid oil, i.e. oil that has undergone an intense oxidation process.
Other negative attributes that can be found in oil are: Cooked or overcooked, hay – wood, coarse, lubricants, vegetation water, brine, metallic, dry grass, worms and cucumber.
